Cutting Board Finish Revisited
Article - December 2, 2007
Seems like cutting boards are on everyone’s minds these days. Probably because we are all making holiday gifts. Either way, this is the time of year you can expect almost one forum post a day asking a question about cutting board finishes or “food safe” finishes. And the responses to these posts are nearly always the same:
Person 1- The best finish for a butcher block is mineral oil.
Person 2- NEVER use varnish or salad bowl finish on a cutting board! What are you, stupid?!?!
Person 3- Mineral oil and wax are the best!
Person 4- This person usually provides a bunch of extra information that you didn’t ask for.
Ok so I am generalizing here for fun, but you get the picture. I have noticed as well that many of the people posing these questions may be doing so because of my advice from Episode 7- A Cut Above. To sum up, I said that my favorite finish for end grain butcher blocks is salad bowl finish (aka varnish). But remember my caveat. I said we are NOT trying to build a film. And that’s exactly what the folks in the forums are trying to say. If you build a film, the film will then be cut by a knife. The cut will allow moisture to seep under the finish and become a wonderful home for all kinds of bacteria. I can’t disagree there. But with my method, you never actually build an appreciable film.
I recommend diluting the finish sufficiently so that it immediately gets absorbed into the wood’s wide open pores. Think of it like a vertical bunch of straws that you are filling up with finish. Within a minute or two, you will notice that finish is actually seeping out of the bottom of the board. This is exactly what we want. At this point, I usually set board on its side and allow it to dry overnight. I do this 3-4 times with a light sanding in between each session. By the final coat, you should start noticing that the finish doesn’t really absorb any more. You are now starting to develop a film. One last wipe with a clean cloth and call it DONE.
So how does a board like this fare in the kitchen? There are two main concerns here: safety and maintenance. A butcher block treated this way will resist water all day long. In fact, on my boards, water tends to evaporate faster than it absorbs. Mineral oil boards will actually take on moisture much more readily. Adding wax to your mineral oil can certainly help in this area if thats the route you want to go. Now the fact that it is so water resistant is a major plus in terms of sanitation. Remember that the bacteria like the moisture. So the less moisture in the board, the better.
So how about knife marks? Well like with any board, knife marks will happen. If they don’t, you must not be using your board properly. So what happens to my boards? They get knicked up. They get dulled a little more in the middle where the most action occurs. But after about 18 straight months of usage, my cutting board looks pretty darn good. Check out the pics below. Now if there were a thick film on that board and that film were to crack, the moisture would certainly seep in and create problems. In fact after 18 months of that type of abuse you would probably expect the finish to start flaking off or exhibit more physical damage than what you see. But when a knife produces a deep cut on my board, it just cuts into varnish-filled pores. There is nothing to flake off.
Now let’s talk about maintenance. I haven’t done anything to that board other than a light soap and water scrub after each use, and an occasional white vinegar rub down. And I suspect that in another month or so, I will take the board back in the shop, give the top a nice thorough sanding, reapply a light coat or two of diluted varnish (monitoring how much it takes up), and the board will look brand new. What kind of maintenance does a mineral oil board require? Monthly, and possibly more frequently if used heavily. Maybe I’m just lazy but one of those maintenance schedules sounds a whole lot more fun than the other.
I am by no means trying to discourage people from using mineral oil. After all, its the classic cutting board finish. Use whatever floats your boat. Personally, I have had great success with my method and will continue to use it. The feedback from other folks who have tried it has been great as well. I think its safer, easier, and looks better. Of course my results are not backed by scientific tests. If I still worked in a lab I might be able to test it properly. But I can’t, so all I can do is speculate and bring a little common sense to the table. Finishing is, and probably always will be, one of the most over-complicated and misunderstood areas of woodworking. I only wish there were more scientific resources out there so that issues like this can be resolved effectively without speculation. Until then, do your research and never count on my advice or anyone else’s as cold hard fact. Gather as much information as possible from your trusted resources and then add the final ingredient: YOUR experience, opinions, and common sense.
Viva La Varnished Board!